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speedometer rpm gauge needles going crazy
Engine throttle valve failure, idle speed control valve failure, air leakage of engine intake mechanism, carbon deposition of engine, charging line failure, etc. may occur, thus causing the tachometer to drop suddenly. Recommend sending the car to the 4S store for repair.
During driving, the engine speed rises and falls as follows.
1. Defective charging line
Charger failure may be caused by generator failure, battery pack voltage sensor failure and battery pack looseness.Because the generator needs to charge the battery when the car is running. When the battery cannot be charged or fully charged, the engine ECU will increase the engine speed, let the generator charge the battery, and make the tachometer jump up and down during driving.
2.There is something wrong with this throttle.
The throttle valve fault may be the fault of the throttle position sensor or the throttle control motor. Just like its name, the throttle position sensor can detect the opening of the throttle and adjust the fuel injection. The function of the throttle control motor is to open the throttle at a certain angle according to the depth of the throttle.If both components fail, the intake air of the engine will change, causing the speedometer to jump up and down when the car is running.
3.Fault of positive crankcase ventilation valve or carbon canister solenoid valve.
A PCV valve, i.e. positive crankcase ventilation valve, is used to return the combustible mixture blown to the cylinder to the inhaler for combustion. The carbon canister solenoid valve is used to burn gasoline from the fuel tank to the cylinder, thus reducing fuel consumption.
If the two valves fail, the fuel burned in the cylinder will be separated from the ECU device, and the tachometer will jump up and down. When stepping on the accelerator, when the rotation speed is up and down, first check whether the fault light in the instrument panel is on. If it is not on, it means that the sensor is OK, which may be caused by insufficient power supply voltage, air leakage from the intake manifold, idling of the motor, etc. If you need to check the problems of the car yourself, you can first open the engine cover of the car and remove the air filter of the throttle; Then start the car and block the throttle. If the car does not stop after blocking, check the nearby pipes to see if there is any suction. If there is, it means that there is an air leak, and it needs to be replaced.
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